There is a folder named $WINDOWS.~BT on the root of my C: drive. It is a hidden folder and is 75 MB in size.
What is its purpose? Is it safe to delete it?
Solution:
This seems to be Windows update logs & files.
It includes files to upgrade Windows, and also, once you do upgrade, the old OS goes into that folder
It should be perfectly safe to delete it, as long as you don’t want to upgrade or downgrade Windows.
However, you can’t do it the normal way.
Instead,
a) Press Windows key + R
b) Type: %windir%system32cleanmgr.exe
c) Hit Enter on your keyboard
Edit: This method seems to only delete some things in this folder, some may be left over. See the other answer for a more complete removal method, though that isn’t perfect, either. Additionally, this may help: How to delete trustedinstaller files on Windows 8
Sources:
- http://answers.microsoft.com/en-us/windows/forum/windows_8-windows_install/how-do-i-delete-windowsbt-after-failed-windows-8/d15416e8-fd5a-4d4e-b04b-5907a4f6c623
- John (see comments)
- FranKee (see comments)